Zinc is both abundant in the diet and in the environment that is why its nutritional significance has not been recognized until the antagonists that limited its bioavailability were identified. On the other hand, in the fear of becoming deficient, many tended to eat its rich sources which resulted in the extreme level of zinc in the body. In 1991, the UK Panel on Dietary Reference Values highlighted the need for a reliable means of assessing zinc status. Salgueiro et al. (2000) also stated that the lack of a reliable method to assess zinc nutritional status interferes with the diagnosis of zinc deficiency and the estimation of RDA. Thus, the study was conducted. Two experimental researches were performed in 35-week old roosters; one was forced fed with zinc oxide while the other with zinc methionine. Collection of blood was made via the wing vein at 30-minute interval for 180 minutes. Results show that forced feeding with the said minerals neither in the form of zinc oxide nor in the form of zinc methionine did not affect the plasma zinc concentration. The study concludes that the zinc used have no effect on the plasma zinc concentration. It is recommended therefore not to use the latter in determining the body’s zinc concentration.